Reading the numbers
Why sources disagree, which number to trust for what, and how the site works.
Why do Zillow, Redfin and the MLS show different numbers for the same place?
They measure different things, and four differences usually explain the gap:
- What is measured. Zillow's Home Value Index estimates what a typical home is worth, sold or not. Redfin and the MLS (CTAR) report the median price of homes that actually sold.
- Where. Redfin and Zillow use town limits. CTAR uses its own MLS market areas, which ignore town lines. CTAR's James Island area covers the whole island, including City of Charleston neighborhoods like Riverland Terrace; the Town of James Island is a smaller, less expensive slice.
- Which homes. CTAR splits single-family houses from townhouses and condos. Redfin town figures mix all home types, and condos pull the median down.
- When. CTAR reports one month. Redfin uses a 3-month rolling window. Zillow is smoothed over time. One month with a few big waterfront sales can jump $100,000 or more.
Example, August 2026: CTAR's James Island single-family median was $800,000 (42 sales, whole island, one month). Redfin's Town of James Island median was about $605,000 (all home types, June to August). Zillow's typical value for ZIP 29412 was about $598,000. All three are correct.
Which number should I use?
- Buying or selling a house: CTAR's single-family figures for your market area, looked at over several months (turn on the 3-month smoothing in the dashboard).
- Tracking what your home is worth over time: Zillow's home value index for your town or ZIP. It moves smoothly and goes back to 2000.
- How fast homes are selling: days on market and months of supply from Redfin or CTAR.
What's the difference between a town, a market area and a neighborhood here?
Towns follow official town and city limits. Market areas are the local MLS's own zones (for example, "West Ashley" or "James Island"), which cross town lines. Neighborhoods are grouped by where they physically sit, so Riverland Terrace is listed under James Island even though it is inside City of Charleston limits.
Why do some towns and areas jump around so much?
Small places have few sales. When a median is based on a handful of homes, one expensive or cheap sale moves it a lot. We flag small samples with an asterisk (*). For small areas, look at the trend over several months rather than the latest dot.
Why does James Island use a ZIP code for Zillow values?
Zillow doesn't publish a series for the Town of James Island, so we use its ZIP code 29412, which contains the whole town. Rockville uses its ZIP 29487 for the same reason.
How often is the data updated?
Monthly. Zillow, Redfin and the MLS publish the previous month's data in the first half of each month, and the site is refreshed after that. Mortgage rates come from Freddie Mac's weekly survey.
Is this investment or real estate advice?
No. Cape Island Point Research is an independent publication. We aren't a brokerage, lender or agent. Use the numbers as a starting point, and talk to a professional about your specific situation.
I found a mistake. How do I report it?
Email brandon@capeislandpoint.com and it will be fixed in the next update.